20857680505 has 8 divisors (see below), whose sum is σ = 25031506824. Its totient is φ = 16684617600.

The previous prime is 20857680497. The next prime is 20857680551. The reversal of 20857680505 is 50508675802.

It can be written as a sum of positive squares in 4 ways, for example, as 13532203584 + 7325476921 = 116328^2 + 85589^2 .

It is a sphenic number, since it is the product of 3 distinct primes.

It is not a de Polignac number, because 20857680505 - 2³ = 20857680497 is a prime.

It is a Duffinian number.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 128916 + ... + 241525.

It is an arithmetic number, because the mean of its divisors is an integer number (3128938353).

Almost surely, 2^20857680505 is an apocalyptic number.

It is an amenable number.

20857680505 is a deficient number, since it is larger than the sum of its proper divisors (4173826319).

20857680505 is a wasteful number, since it uses less digits than its factorization.

20857680505 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 381707.

The product of its (nonzero) digits is 672000, while the sum is 46.

The spelling of 20857680505 in words is "twenty billion, eight hundred fifty-seven million, six hundred eighty thousand, five hundred five".